AIM: To observe the effects of catechin microcapsule on the immune functions of normal and immunosuppressed mice. METHODS: The immunosuppressed mice were induced by cyclophosphamide(CY) and catechin microcapsule taken orally.The immunodulatory effects were measured by delayed type hypersensitivity(DTH) , HC 50 value and cleaning charcoal partical method. RESULTS: Degrees of oncotic (36±7)mg of high dose group catechin microcapsule(500 mg·kg -1·d -1)mouse were significantly intensified caused by DNFB in comparing with(20±3) mg of NS group(P<0.01).The K,α (0.053 3± 0.0025,7.08±0.03)of mouse were improved in comparion with (0.041 2± 0.0028; 6.16±0.19)of NS group(P<0.01); Degrees of oncotic (19±3)mg of CY 80 mg·kg -1·d -1 + catechin microcapsule 500 mg·kg -1·d -1 mouse were significantly intensify caused by DNFB,comparing with (9±4) mg of CY group(P<0.01). HC 50(223±15) of CY 80 mg·kg -1·d -1 + catechin microcapsule 500 mg·kg -1·d -1 mouse were increased in comparing with (193±18) of CY group(P<0.01). The K,α(0.034 8± 0.002 8;6.01±0.11)of mouse were improved in carrelation with(0.023 8±0.003 6; 5.1±0.6)of NS group(P<0.05). CONCULSION: Catechin microcapsule has an enhanced effect on cell-mediated immunity and humoral immunity of normal and immunosuppressed mice.